Based upon statistics of sediment parameters and sediment moving modes from probability cumulative distribution curves, and combined with topography and hydrodynamics, the sedimentary environment at the intertidal flats of Qing 8 estuary (1996-now) and Diaokou estuary (1964-1976) at the Yellow River Delta was discussed in depth in present study. The results demonstrated that sediment grain size parameters can clearly reveal hydrodynamic condition of the sedimentary environment. Core C1 at current estuary was divided into four layers. The corresponding hydrodynamic conditions from top to bottom varied from strong to fluctuating between strong and weak, and finally to weak. Meanwhile, Core A1 at abandoned estuary can be divided into three layers and corresponding hydrodynamics from top to bottom changed from fairly strong to rather strong. Furthermore, the sedimentary facies of two cores were identified and they depended on water and sediment discharge from the Yellow River.